Yuko Yoneda

Publications of Yuko Yoneda

• Van der Waals versus hydrogen-bonding forces in a crystalline analog of cellotetraose: cyclohexyl 4'-O-cyclohexyl beta-D-cellobioside cyclohexane solvate.

  Authors: Yuko Yoneda, Kurt Mereiter, Christian Jaeger, Lothar Brecker, Paul Kosma, Thomas Rosenau, Alfred French

  Journal of the American Chemical Society. 01/2009; 130(49):16678-90.

  Hydrogen bonding is important in cellulosic and other carbohydrate structures, but the role of interactions between nonpolar groups is less understood. Therefore, we synthesized cyclohexyl 4'-OHydrogen bonding is important in cellulosic and other carbohydrate structures, but the role of interactions between nonpolar groups is less understood. Therefore, we synthesized cyclohexyl 4'-O cyclohexyl beta-D-cellobioside (8), a molecule that has two glucose rings and two nonpolar cyclohexyl rings. Key to attaching the 4'-Ocyclohexyl group was making the 4'-O,6'-O-cyclohexylidene ketal. After peracetylation, the cyclohexylidene ketal ring was opened regioselectively, providing 65% of 8 after final deacetylation. Comparison of the crystal structure of 8, as the cyclohexane solvate, with those of cellulose and its fragments, especially cellotetraose with four glucose rings, revealed extensive effects from the cyclohexyl groups. Three conformationally unique molecules (A, B, and C) are in the triclinic unit cell of 8, along with two solvent cyclohexanes. When viewed down the crystal's a-axis, the array of C, A, and B looks like the letter N, with A inclined so that its cyclohexyl groups can stack with those of the reducing ends of the B and C molecules. The lower left and upper right points of the N are stacks of cyclohexyl rings on the nonreducing ends of B and C, interspersed with solvent cyclohexanes. Whereas cellotetraose has antiparallel (up-down) packing, A and B in 8 are oriented "down" in the unit cell while C is "up". "Down-down-up" (or, alternatively, "up-up-down") packing is rare for carbohydrates. Other unusual details include 06 in all three staggered orientations: one is tg, two are gg, and three are gt, confirmed with CP/MAS 13C NMR. The tg O6 donates a proton to an intramolecular hydrogen bond to O2', opposite to the major schemes in native cellulose I. A similar but novel O6B-H...O2'B hydrogen bond is based on a slightly distorted gg orientation. The hydrogen bonds between parallel molecules are unique, with linkages between O2'A and O2'B, O3'A and O3'B, and O6A and O6B. Other details, such as the bifurcated O3...O5' and ...O6' hydrogen bonds are similar to those of other cellulosic structures. C-H...O hydrogen bonds are extensive along the [110] line of quarter-staggering. The unusual features described here expand the range of structural motifs to be considered for as-yet undetermined cellulose structures.

• Synthesis of methyl 4'-O-methyl-beta-D-cellobioside-13C12 from D-glucose-13C6. Part 2: solid-state NMR studies.

  Authors: Frank Malz, Yuko Yoneda, Toshinari Kawada, Kurt Mereiter, Paul Kosma, Thomas Rosenau, Christian Jäger

  Carbohydrate research. 02/2007; 342(1):65-70.

  Double Quantum (DQ) NMR, which utilizes the magnetic dipole interaction between the (13)C atoms, was used for the complete assignment of the (13)C NMR resonances to the corresponding carbon ringDouble Quantum (DQ) NMR, which utilizes the magnetic dipole interaction between the (13)C atoms, was used for the complete assignment of the (13)C NMR resonances to the corresponding carbon ring positions for the monoclinic and triclinic allomorphs of methyl 4'-O-methyl-beta-D-cellobioside-(13)C(12)(1-(13)C(12)), a cellodextrin model compound of cellulose (13)C-perlabeled at the cellobiose core. The through-space interactions were used to identify the direct chemical bonds between adjacent carbon atoms in the rings. More importantly, the (13)C NMR signals of the carbon sites C1' and C4 involved in the glycosidic bond were identified. This allowed for the complete (13)C chemical shift assignment, that when combined with the X-ray crystallography data provides a complete characterization.

• Synthesis of methyl 4'-O-methyl-13C12-beta-D-cellobioside from 13C6-D-glucose. Part 1: reaction optimization and synthesis.

  Authors: Yuko Yoneda, Toshinari Kawada, Thomas Rosenau, Paul Kosma

  Carbohydrate research. 11/2005; 340(15):2428-35.

  A high yielding synthetic route for methyl 4'-O-methyl-beta-D-cellobioside starting from d-glucose was established. The reaction conditions optimized with nonlabeled materials were used for theA high yielding synthetic route for methyl 4'-O-methyl-beta-D-cellobioside starting from d-glucose was established. The reaction conditions optimized with nonlabeled materials were used for the synthesis of methyl 4'-O-methyl-13C12-beta-D-cellobioside, a compound having more than 99% 13C enrichment at each of the twelve pyranose carbon atoms. The labeled compound is required to study the hydrogen bond network of cellodextrins and cellulose by CPMAS NMR experiments.

• van der Waals versus Hydrogen-Bonding Forces in a Crystalline Analog of Cellotetraose: Cyclohexyl 4'-O-Cyclohexyl β-D-Cellobioside Cyclohexane Solvate.

  Authors: Yuko Yoneda, Kurt Mereiter, Christian Jaeger, Lothar Brecker, Paul Kosma, Thomas Rosenau, Alfred French

  Hydrogen bonding is important in cellulosic and other carbohydrate structures, but the role of interactions between nonpolar groups is less understood. Therefore, we synthesized cyclohexylHydrogen bonding is important in cellulosic and other carbohydrate structures, but the role of interactions between nonpolar groups is less understood. Therefore, we synthesized cyclohexyl 4'-O-cyclohexyl β-d-cellobioside (8), a molecule that has two glucose rings and two nonpolar cyclohexyl rings. Key to attaching the 4'-O-cyclohexyl group was making the 4'-O,6'-O-cyclohexylidene ketal. After peracetylation, the cyclohexylidene ketal ring was opened regioselectively, providing 65% of 8 after final deacetylation. Comparison of the crystal structure of 8, as the cyclohexane solvate, with those of cellulose and its fragments, especially cellotetraose with four glucose rings, revealed extensive effects from the cyclohexyl groups. Three conformationally unique molecules (A, B, and C) are in the triclinic unit cell of 8, along with two solvent cyclohexanes. When viewed down the crystal's a-axis, the array of C, A, and B looks like the letter N, with A inclined so that its cyclohexyl groups can stack with those of the reducing ends of the B and C molecules. The lower left and upper right points of the N are stacks of cyclohexyl rings on the nonreducing ends of B and C, interspersed with solvent cyclohexanes. Whereas cellotetraose has antiparallel (up-down) packing, A and B in 8 are oriented "down" in the unit cell while C is "up". "Down-down-up" (or, alternatively, "up-up-down") packing is rare for carbohydrates. Other unusual details include O6 in all three staggered orientations: one is tg, two are gg, and three are gt, confirmed with CP/MAS 13C NMR. The tg O6 donates a proton to an intramolecular hydrogen bond to O2', opposite to the major schemes in native cellulose I. A similar but novel O6B-H···O2'B hydrogen bond is based on a slightly distorted gg orientation. The hydrogen bonds between parallel molecules are unique, with linkages between O2'A and O2'B, O3'A and O3'B, and O6A and O6B. Other details, such as the bifurcated O3···O5' and ··O6' hydrogen bonds are similar to those of other cellulosic structures. C-H···O hydrogen bonds are extensive along the [110] line of quarter-staggering. The unusual features described here expand the range of structural motifs to be considered for as-yet undetermined cellulose structures.